Wash Your Hands, Yes. But How You Dry Them Matters Too

With flu season right around the corner, your mother, doctor and HR manager will no doubt be reminding you of the usual preventive measures: Get a flu shot. Cover your nose and mouth when you cough or sneeze. Wash your hands with an alcohol-based hand sanitizer or, even better, with soap throughout the day. But there’s something else. Another step to ensuring virus-free hands: making sure they’re dry. (More on Time.com: Post-H1N1, Why You Still Need to Worry About Flu)

A new University of Bradford study published in the Journal of Applied Microbiology found that wet hands after washing increases the spread of bacteria:

The degree of wetness of hands appears to greatly influence bacterial transfer and dissemination to surfaces and items touched. This probably occurs not only because of the physical aspects of moisture droplets transferring between one surface and another but also because the bacteria may be maintained in a physiological state that makes them better able to survive in the new environment.

“Good hand hygiene should include drying hands thoroughly and not just washing,” says Anna Snelling, the study’s lead researcher and an expert in microbiology and infection control.

The study’s researchers asked 14 volunteers to handle raw chicken meat, wash their hands with soap, and then dry their hands with paper, conventional dryers, one of those newfangled Dyson Airblade dryers, or by simple drip-drying. Afterward, the participants were instructed to touch pieces of sterile aluminum foil, which the researchers then analyzed to measure the amount of bacteria transferred. (More on Time.com:Want Good Health? There Are 10 Apps for That)

The results: patting your hands dry with paper is best. The new Airblade jet dryers, which do the drying work for you by forcefully stripping moisture away from your hands, came in second. And traditional air dryers came last, because people tend to use a rubbing motion under the air stream. The rubbing, the authors say, actually makes bacteria previously embedded in the skin come to the surface.

The study was small and funded by Dyson. But the findings are in line with past research — which, granted, was for the tissue paper industry, but who else would you expect to study this stuff? — by Keith Redway, a microbiologist at the University of Westminster. Redway agrees that paper is more hygienic than air dryers, but acknowledges that the suggestion to refrain from rubbing hands is unusual. “It’s not normal behavior,” Redway said. “The great majority do rub their hands to speed up the drying process.”

If you’re more concerned with avoiding the flu than fast-drying, however, then it might not hurt to grab a paper towel or take a few extra moments at the hand dryer next time.